1. Field of the Invention
The present invention relates to a method for producing a rare earth sintered magnet.
2. Related Background Art
Rare earth sintered magnets are typically produced by press molding raw materials having specific compositions to produce molded bodies and then calcining the molded bodies. Wet molding using slurry as a raw material for producing a molded body is developed as a method for producing a rare earth sintered magnet in order to, for example, improve the magnetic properties. The main factor of using this technique is that wet molding can improve the uniformity of magnetic powder as compared with dry molding. As described above, the production condition of a molded body largely affects the properties of a rare earth sintered magnet.
Typically, for producing an anisotropic rare earth sintered magnet by the wet molding technique as described above, molding in a magnetic field by which a material is applied with a magnetic field while being pressurized is performed to produce a molded body in which the magnetic particles are oriented by the magnetic field in a predetermined direction. During this process, binding between the magnetic powder particles and a magnetic field orientation are simultaneously performed.
A technique for performing injection molding after a thermoplastic binder and magnetic powder are kneaded is developed as another method for producing a molded body for a rare earth sintered magnet (for example, see Patent document 1). Typically, a kneaded product needs to be heated during molding in such a production method.
[Patent document 1] Japanese Unexamined Patent Publication No. JP-A-H9-283358